1. Field of the Invention
The present invention relates to a lever-type measuring machine.
2. Description of Related Art
A lever-type measuring machine is known for measuring a shape or surface roughness of a machine-tooled workpiece. To measure a shape of an object, the lever-type measuring machine has a gauge head, an arm, and a balancer, the gauge head being substantially perpendicularly brought into contact with a surface of the object, the arm having the gauge head fixated thereto, the balancer supporting the arm.
In a technology disclosed in Japanese Patent Laid-Open No. 2001-241905, for example, a stylus of a detector is brought into contact with a peripheral surface of a workpiece and the detector is rotated to measure roughness of the peripheral surface of the workpiece. The detector disclosed in Japanese Patent Laid-Open No. 2001-241905 is swingably supported by a rotation axis member rotationally driven by a drive member. The detector has a balance weight that counterbalances the detector around a supporting point.
The contact-type measuring machine is configured such that the stylus swings up and down centering the supporting point. Thus, in order to improve accuracy of the contact-type measuring machine, swing responsiveness of the stylus with respect to unevenness of the surface of the object needs to be improved.
A known lever-type measuring machine for better responsiveness has a ceramic arm. FIG. 6 is an overview of a lever-type measuring machine having conventionally an arm portion composed of a ceramic. A lever-type measuring machine 200 has a stylus 201, an arm 202, and a balancer 203. The balancer 203 is composed of an easily processed metal, such as aluminum.
In the lever-type measuring machine 200, the arm 202 is composed of a ceramic. The arm 202 is lighter than an arm composed of a metal or metal compound. Accordingly, the balancer 203 connected to the arm 202 is also reduced in weight to counterbalance the arm 202. The balancer 203 composed of a metal or the like is generally processed so as to be thin in a longitudinal direction.
However, vibration is likely to be generated in the thin direction of the thin balancer 203. When vibration is generated in the balancer 203, the vibration is transmitted from the balancer 203 to the arm 202 and from the arm 202 to the stylus 201, thus affecting measurement.